1. Technical Field
An exemplary embodiment relates to magnetic resonance imaging apparatus (hereinafter, referred to as “MRI apparatus”) configured to perform a positioning operation of desired imaging areas of heart automatically.
2. Description of Related Art
A cardiac MRI examination is complex and takes a relatively long time, and requires expert proficiency for executing the examination and interpretation of the resulting radiogram image. Therefore, SCMR (Society for Cardiovascular Magnetic Resonance), which is an international society for Cardiac MRI has determined a standardized protocol for cardiac MRI examination. This standardized protocol includes not only a sequence used for the cardiac MRI examination and imaging conditions such as slice thicknesses tailored to diseases or objects of the examination, but also a detailed operating procedure for positioning of desired imaging areas of heart, which are different from subject to subject and required for a preparation of the cardiac MRI examination.
The operating procedure for positioning of the desired imaging areas of heart included in the standardized protocol using an MRI apparatus as a background (hereinafter referred to as a “background apparatus”) will be described briefly with reference to FIG. 1 to FIG. 7. The procedure described from now on is focused only on a position of the imaging area, and the imaging conditions such as the sequence are omitted.
In FIG. 1, a flowchart is shown for an operating procedure to acquire a cross section of a four-chamber long-axis view (or a four-chamber cross-sectional view) position included in the standardized protocol as an example of an operating procedure for positioning the desired imaging areas of the heart.
First of all, in Step S1-1, the background apparatus acquires images of scout views. The term scout views in an imaging range 10 of a subject 1 shown in FIG. 2A includes images of a body axis cross-sectional plane 10a, a sagittal section 10b, and a coronal section 10c in the imaging range 10 as shown in FIG. 2B. Images 11a, 11b, and 11c of the scout views are generally referred to as an Axial view (see FIG. 2C), a Sagittal view (see FIG. 2D), and a Coronal view (see FIG. 2E), respectively.
Subsequently, in Step S1-2, the background apparatus acquires Multi Slice views. The term Slice views refers to N shots of body axis cross sections 10d1, . . . , 10dN which cover a chest portion as shown in FIGS. 3A-3B.
Subsequently, in Step S1-3, the background apparatus selects an arbitrary nth image 11dn from the N shots of Multi Slice views as shown in FIG. 4A, and a long axis vector 20a passing from the image 11dn through a center of a mitral valve to a cardiac apex. Then, the background apparatus acquires an image of a cross section 10e passing the long axis vector 20a and extending in parallel to a direction of a body axis (see FIG. 4B). An image 11e of the cross section 10e is referred to as a vertical long-axis view (see FIG. 4C).
Subsequently, in Step S1-4, the background apparatus sets a long axis vector 20b passing from the image 11e through the center of the mitral valve and the cardiac apex as shown in FIG. 5A, and acquires an image of a cross section 10f passing through the long axis vector 20b and orthogonal to the cross section 10e (see FIG. 5B). As shown in FIG. 5C, an image 11f of the cross section 10f is referred to as a horizontal long-axis view.
Subsequently, in Step S1-5, the background apparatus sets a long axis vector 20c passing from the image 11f through the center of the mitral valve and the cardiac apex as shown in FIG. 6A, and acquires M shots of images of cross sections 10g1, . . . 10gM orthogonal to both of the long axis vector 20c and the cross section 10f (see FIG. 6B). A range of the cross section 10g is from the mitral valve to the cardiac apex. As shown in FIG. 6B, the images of the cross sections 10g1 to 10gM are referred to as left chamber short-axis views.
Finally, in Step S1-6, the background apparatus sets a short axis vector 21a passing from an arbitrary left chamber short-axis view 11gm close to a base of heart through a center 20d of a left chamber to a corner of a right ventricle as shown in FIG. 7A, and acquires an image of a cross section passing through the short axis vector 21a and orthogonal to the cross section 10gm. As shown in FIG. 7B, an image 11h of this cross section is referred to as four-chamber long-axis view.
However, in the operating procedure for positioning of the desired imaging areas of heart, for example, when the desired cross section is the four-chamber long-axis view, it is necessary to acquire images five times in total from Step S1-1 to Step S1-5 and to five times of set imaging positions and ranges in order to perform the positioning operation. In other words, the subject 1 is required to stop breathing several times in order to perform the positioning operation of the imaging areas as the preparation of the cardiac MRI examination (five times in the case of the four-chamber long-axis view, four times in the case of the left chamber short-axis view), and an operator of the background apparatus is required to perform setting operations a plurality of times for setting positions of the cross sections.